Process for improving the magnetic qualities of iron-silicon-manganese-aluminium alloys.



, the alloy to a temperatureabove a critical.

- the same slowly. When said alloy is sub- UNITED STATES PATENT OFFICE.

ROBERT ABBOTT HAIDFIELD,

0F SHEFFIELD, ENGLAND.

IBOCESS FOR IMPROVING THE MAGNETIC QUALITIES 0F IRON-SILICON-MANGANESE- ALUMINIUM ALLOYS.

1,086,765. Specifiation of Letter-5 Patent Patented Feb. 10, 191-4.

Ito-Drawing. Application filed March 21, 1907, Serial No. 868,663. Renewed .Tune 27, 1913. Serial No.

To all whom it may concern: I-clai'm: I

Be it known that I, ROBERT A. Hsnrmm, a subject of the King of Great Britain and Ireland, residing at Parkhead, Sheflield, England, have invented a certain new-and useful Improvement in Processes for Imroving the Magnetic Qualities of Iron- S ilicon-Manganese-Aluminium Alloys, of which the following is a specification.

In .17. S. Letters Patent No. 842,403, granted to me January 29, 1907, I'have described and claimed an iron-silicon-manganese -aluminium alloy, containing silicon from 2 1304.5 per cent., manganese not exceeding .7 per cent. and aluminium not exceeding 1.3 per cent. Said alloy is especially adaptable for use in ballast coils, transformer plates or like electric apparatus. In order to effect the best reduction of the magnetic and electric losses in such alloy a heat treatment thereof isnccessary.

My present invention is a process of heat treatment applied to the aforesaid iron-silicon-manganese-aluminium alloy for the purpose stated.

In carrying my present invention into effect, I prepare the said alloy as set forth in my patent aforesaid, cast the same in ingots in the usual way, convert the ingots into desired shapes and thicknesses and heat point (hereinafter defined) and then 0001 jected to progressive temperature variations (below fusion), it undergoes, ata certain temperature point, an apparent molecular change, and on further alteration of temperature, another oint ensues at which another molecular c ange occurs. The term critical point, herein used, means the point of higher temperature of the two above noted, and approximates to the 900 centigrade oint in the case of pure iron, which is t e lower limit of its so-called gamma state. For certain purposes also, ifdesired, the material as cast may be used being suitably treated in the same manner as forged or rolled material.

The material herein referred to is low in carbon.

1. The rocess of increasing the magnetic permeability and electric resistance and reducing the hysteresis action of an iron alloy containing silicon from about 2 to 4.5 per cent., manganese, under about .7 per cent., and aluminium under about 1.3 per cent. which consists in heating said alloy above the critical point approximating 900 C. in the case of pure iron and then cooling slowly.

2. The process of increasing the magnetic permeability and electric resistance and reducing the hysteresis action of an iron silicon-manganese-aluminium alloy containing silicon from about 2 to about 4.5% which consists in heating said alloy above the critical or gamma point and then allowing it to cool slowly.

3. The herein described process of producing an alloy of high magnetic permeability and electric resistance and low hys-- teresis action, which consists in alloying iron with silicon, aluminium and manganese under about .7 heating said alloy above the gamma or critical point and then permitt-ing it to cool slowly.

4. The herein described process of producing an alloy of high magnetic permeability and electric resistance and low hysteresis action which consists in alloying iron with silicon, manganese and alummium under about 1.3%, heating said alloy above the critical or gamma point and then permitt-ing it to cool slowly.

5. The process of increasing the magnetic permeability and electric resistance and reducing the hysteresis action of an iron alloy containing s licon from about 2 to 4.5 per cent., manganese under about .7 per cent., and aluminium under about 1.3 per cent.

.which consists in heating said alloy above the critical point approximating 90( C. in the case of pure iron and then cooling.

In testimony whereof I have afiixed my signature in presence of two witnesses.

ROBERT ABBOTT HADFIELD.

Witnesses:

HUGH HUGHES, WM. 0. BROWN. 

